ACIL Tasman considered it reasonable to assume that some 15,000GWh of new generation could be supported by 2016/17 giving a potential gas-fired output for that year of around 35,000GWh, according to ‘Fuel resource, new entry and generation costs in the NEM’, a report to NEMMCO by ACIL Tasman (27/3/2007).

Capacity factors: A further 15,000GWh should be achievable by 2026/27, bringing the potential gas-fired generation for that year to around 50,000GWh. The MW capacity of CCGTs (combined cycle gas turbines) which could be supported would depend on the capacity factors achieved by the gas-fired stations which could range from as low as 50 per cent on average to as high as 90 per cent. Assuming a capacity factor of say 50 per cent suggests that some 3,400MW (nine 380MW CCGTs) could be supplied with competitively priced gas in the 10 years to 2016/17 and 6,800MW (18x380MW CCGTs) in the 20 years to 2026/27.

Location factors: The possible location of these CCGTs depended inter alia on the availability of gas in each zone. The capacity to supply CCGTs was the same in many adjoining zones such as SEQ & SWQ or LV & MEL and in these cases the capacity to supply a number of CCGTs was provided for both zones together. The actual zonal location would then depend on gas price and other considerations. Based on the above discussion, the total number of CCGTs should be limited to nine in the 10 years to 2016/17 and to 18 in the 20 years to 2026/27.

Importing from other field: The fact that the total number of potential plants in zones was considerably more than the overall limits reflected the fact that gas can be used for a multitude of purposes. For example, if all 6 potential CCGTs were installed in SEQ & SWQ (southeast/west Queensland) in the period to 2016/17 then that would reduce the zones’ capability to satisfy other gas demands in these or other zones and raised the prospect that gas for other uses may need to be imported from further afield, the report added.